1. Field of Invention
The present invention relates to a variable frequency modulation technique with the power electronic devices. More particularly, the present invention relates to a high-power medium-voltage drive power cell.
2. Description of Related Art
With the rapid development of the modern power electronic technology and microelectronic technology, the medium-voltage high-power variable frequency control device has been used more and more widely, such as various wind generators, water pumps, compressors, rolling machines used in various industries such as petrochemical engineering, municipal water supply, ferrous metallurgy and electric energy.
In the prior art, a power cell with relatively independent functions is an important part of a cascaded medium-voltage drive, and is also a key part for performing the medium-voltage frequency control, which not only has to consider heat dissipation and ventilation, but also has to take in account various factors such as a compact structure, a proper layout, convenient assembly and maintenance.
Currently, most of the heat dissipation designs for the high-power medium-voltage drive adopt an aluminum extrusion heat sink, and all of the power elements are placed on the base of heat sink. This structure causes high heat dissipation requirements. When a large-scale heat sink is used, the distance between modules is relative large, and the layout is non-compact, which causes inconvenience for the electrical connections between the power elements and capacitors. Particularly, when each inverter bridge arm of an inverter bridge is formed from plural IGBTs (Insulated Gate Bipolar Transistors) connected in parallel, the heat dissipation requirements are much higher. Furthermore, the aluminum extrusion heat sink has a large volume and a heavy weight, and a high system cost.
In view of the above, those in the industry are endeavoring to find ways to design a novel high-power medium-voltage drive power cell, for effectively dissipating heat generated from each power element, and meanwhile obtaining a high-power medium-voltage drive power cell with more compactness, more reliable operation and more convenient maintenance.